Spring loaded devices for propelling projectiles such as rods inserted within the devices may be used for various purposes. For example, such devices are commonly used by electricians to aid in the installation of wire or cable at worksites. Electrical wire, telephone wire or other types of wiring often require installation over relatively lengthy worksites. For example, it is often necessary to install wires or cables behind walls, over suspended ceilings, or through openings too narrow for workmen. A wire or thin cable is attached to the projectile within the device and is dispensed as the projectile is propelled towards its destination.
A drag line may first be propelled by wire stringing devices. Wire or cable may then be attached to the drag line and strung to the desired location. Thin wire, however, may be propelled by wire stringing devices without first propelling a drag line.
U.S. Pat. No. 4,056,859 by Pace discloses a spring loaded wire stringing device which propels a dart. The dart carries a fine wire to the desired location. The wire is stored in a dispenser above the barrel of the device until the dart with the wire attached is propelled to the desired location. The device also includes a cutter for cutting the wire after the dart has been propelled to the desired location.
Spring loaded devices are used for projecting a variety of projectiles such as spears as shown in U.S. Pat. No. 3,026,864 by Gray. A spear gun with a safety latch is disclosed in U.S. Pat. No. 3,026,864 which maintains the gun in a cocked position until the safety latch is relieved.
These prior art wire stringing devices do not allow adjustment of the compression of the compression spring, the conventional power source used for propelling the projectile, and at the same time provide a safety catch.